docs: def capzone(self, nt=10, zstart=None, hstepmax=10, vstepfrac=0.2,
                  tmax=None, nstepmax=100, silent='.'):
          """Compute a capture zone
          
          Parameters
          ----------
          nt : int
              number of path lines
          zstart : scalar
              starting elevation of the path lines
          hstepmax : scalar
              maximum step in horizontal space
          vstepfrac : float
              maximum fraction of aquifer layer thickness during one step
          tmax : scalar
              maximum time
          nstepmax : scalar(int)
              maximum number of steps
          silent : boolean or string
              True (no messages), False (all messages), or '.'
              (print dot for each path line)
              
          Returns
          -------
          xyzt : list of arrays of x, y, z, and t values
              
          """
          xstart, ystart, zstart = self.capzonestart(nt, zstart)
          xyzt = timtracelines(self.model, xstart, ystart, zstart, -np.abs(hstepmax), \
                               vstepfrac=0.2, tmax=tmax, nstepmax=100, silent='.')
          return xyzt